Frameless PV-module

ABSTRACT

A photovoltaic module employing an array of photovoltaic cells disposed between two optically transparent substrates such as to define a closed-loop peripheral area of the module that does not contain a photovoltaic cell. The module is sealed with a peripheral seal along the perimeter; and is devoid of a structural element affixed to an optically transparent substrate and adapted to mount the module to a supporting structure. The two substrates may be bonded together with adhesive material and, optionally, the peripheral seal can include the adhesive material. The module optionally includes diffraction grating element(s) adjoining respectively corresponding PV-cell(s).

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. Ser. No. 15/886,638 filedFeb. 1, 2018, which is a continuation of U.S. Ser. No. 14/831,651 filedon Aug. 20, 2015, published as U.S. Publication No. 2015/0357495 A1 onDec. 15, 2015, which is a continuation-in-part of U.S. Ser. No.14/488,564 filed on Sep. 17, 2014, now U.S. Pat. No. 9,312,418 issued onApr. 12, 2016, which is a continuation of U.S. Ser. No. 13/775,744 filedFeb. 25, 2013, now U.S. Pat. No. 8,853,525 issued on Oct. 7, 2014, whichclaims priority from U.S. Provisional Patent Applications Nos. (a)61/728,633 filed on Nov. 20, 2012; (b) 61/728,641 filed on Nov. 20,2012; and (c) 61/728,645 filed on Nov. 20, 2012, the entire disclosuresof which are incorporated herein by reference in their entirety.

U.S. Ser. No. 14/488,564 filed on Sep. 17, 2014, now U.S. Pat. No.9,312,418 issued on Apr. 12, 2016, is also a continuation-in-part ofU.S. Ser. No. 13/675,855 filed on Nov. 13, 2012 and titled “FlexiblePhotovoltaic Module”, which claimed priority from U.S. ProvisionalPatent Applications Nos. (a) 61/559,425, filed on Nov. 14, 2011; (b)61/559,980 filed on Nov. 15, 2011; (c) 61/560,381, filed on Nov. 16,2011; (d) 61/562,654 filed on Nov. 22, 2011; and (e) 61/563,339 filed onNov. 23, 2011, the entire disclosures of which are incorporated hereinby reference in their entirety.

TECHNICAL FIELD

The present invention relates to photovoltaic (PV) conversion of solarradiation and, in particular, to a PV modules or panel that is devoid ofa structural frame and/or electrically-grounding element.

BACKGROUND

Solar energy will satisfy an important part of future energy needs.While the need in solar energy output has grown dramatically in recentyears, the total output from all solar installations worldwide stillremains around 178 GW, which is only a tiny fraction of the world'senergy requirement. High material and manufacturing costs, low solarmodule efficiency, and shortage of refined silicon limit the scale ofsolar power development required to effectively compete with the use ofcoal and liquid fossil fuels.

The key issue currently faced by the solar industry is how to reducesystem cost. The main-stream technologies that are being explored toimprove the cost-per-kilowatt of solar power are directed to (i)improving the efficiency of a solar cell that comprises solar modules,and (ii) delivering greater amounts of solar radiation onto the solarcell. In particular, these technologies include developing thin-film,polymer, and dye-sensitized photovoltaic (PV) cells to replace expensivesemiconductor material based solar cells, the use high-efficiencysmaller-area photovoltaic devices, and implementation of low-costcollectors and concentrators of solar energy.

The most common type of a photovoltaic panel in the market is a panelincluding with an (optionally) tempered glass frontsheet, a flexiblebacksheet, monofacial PV elements or cells, and surrounded with astructural frame adapted to impart rigidity on the overall constructionand facilitate mechanical attachment of the panel to a supportingstructure such as a foundation, a roof of a building, or an opening in awall or ceiling.

By configuring a PV module without a frame while not compromising thestructural integrity of the module, the cost of the module andinstallation of the module is significantly reduced. Moreover, however,the frameless module is easier to integrate into structures already usedin the glass and construction industry (as compared to the modulepossessing the frame), thereby making the frameless module easier to usein architectural applications, for example (such as windows orskylights).

SUMMARY

Embodiments of the present invention provide a photovoltaic (PV) modulethat includes (a) a first optically transparent substrate having firstlongitudinal extent defined by first and second edges that aresubstantially parallel to one another, and first transverse extentdefined by third and fourth edges that are substantially parallel to oneanother; and (b) a second optically transparent substrate having secondlongitudinal extent defined by fifth and sixth edges that aresubstantially parallel to one another, and second transverse extentdefined by seventh and eighth edges that are substantially parallel toone another. In such configuration, at least one of the followingconditions is satisfied: (i) a first line representing a normalprojection of the first edge on a plane defined by the second substrateis substantially parallel to and separated from a line representing thefifth edge; and (ii) a second line representing a normal projection ofthe third edge on a plane defined by the second substrate issubstantially parallel to and offset by a second distance from a linerepresenting the seventh edge. The module additionally includes one ormore first PV cells disposed in a volume between the first and secondsubstrates; and, optionally, a first flexible sealing material disposedbetween the first and second substrates along a perimeter of the secondsubstrate to sealingly attach said substrates to one another. In aspecific case, such PV module is devoid of at least one of (i)substantially rigid housing element and (ii) an electrically-conductinggrounding element (which term refers generally to a grounding wire orclamp conventionally configured to electrically attach the module to theracking structure on which the module is mounted. In one implementation,the first and second substrate include congruent curved plates. One ormore first PV cells are electrically interconnected with one another todefine an array of PV cells. Such array has transverse dimensions atleast one of which is smaller than a transverse dimension of the PVmodule, and (when the first flexible material is present) is disposedwithin bounds of the first flexible sealing material to define aperipheral portion of the first volume. The peripheral portion is devoidof a PV cell.

In a specific implementation, the PV module may further include a thirdoptically transparent substrate layer having (i) first longitudinalextent defined by ninth and tenth edges that are substantially parallelto one another, and (i) first transverse extent defined by eleventh andtwelfth edges that are substantially parallel to one another; whereinthe first substrate and the third substrate layer are disposed inparallel to one another and on opposite sides of the second substrate.In such configuration, a first polygon representing a normal projectionof a perimeter of the first substrate on the plane defined by the secondsubstrate is substantially co-extensive with a second polygonrepresenting a normal projection of a perimeter of the third substratelayer on such plane. This specific embodiment also includes one or moresecond PV cells disposed in a volume between the second substrate andthe third substrate layer; and a second flexible sealing materialdisposed between the second substrate and the third substrate layeralong a perimeter of the second substrate to sealingly attach the secondsubstrate and the third substrate layer to one another.

Embodiments of the present invention also provide a photovoltaic (PV)module that contains first and second congruent substrates disposed in aspaced-apart and tangentially-parallel relationship in first and secondplanes, respectively; and a PV layer between the first and secondsubstrates, which PV layer contains at least one PV cell. Here, an outersurface of the first substrate defined by first and second surfaceportions; an outer surface of the second substrate defined by third andfourth portions. The PV module is dimensioned such that, when viewedalong an axis that is perpendicular to both the first and second planes:(a) the first portion does not overlap with any portion of the secondsubstrate; (b) the second and third portions overlap one another, and(c) the fourth portion does not overlap with any portion of the firstsubstrate. The first and fourth portions may be defined on oppositesides of the PV layer. In a specific case, an area of the PV layer isequal to or smaller than the area of the second portion. The embodimentmay also include a first flexible sealing material disposed between thefirst and second substrates along a perimeter of the second substrate tosealingly attach the substrates to one another. Alternatively or inaddition, the PV module may be configured to be devoid of at least oneof substantially rigid housing element and an electrically-groundingelement.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention will be better understood in conjunctionwith the following generally-not-to-scale Drawings, of which:

FIG. 1A is a diagram showing schematically top view of an embodiment ofthe invention;

FIG. 1B is a side view of an embodiment of the invention;

FIG. 1C is a side view of a related embodiment of the invention;

FIG. 1D is a diagram illustrating a top view of an embodiment with firstarrangement of photovoltaic cells in an embodiment of the invention;

FIG. 1E is a diagram illustrating a top view of an embodiment withsecond arrangement of photovoltaic cells in an embodiment of theinvention;

FIG. 2 is a diagram illustrating an alternative arrangement ofphotovoltaic cells in a related embodiment of the invention;

FIG. 3 is a diagram illustrating an alternative arrangement ofphotovoltaic cells in another related embodiment of the invention;

FIG. 4 is a top view of another embodiment of the invention showing analternative arrangement of photovoltaic cells;

FIG. 5A shows a glass substrate containing vias (passes) therethroughfor accommodating of electrical wiring elements of an embodiment of theinvention;

FIG. 5B shows a portion of an embodiment of the invention including thesubstrate of FIG. 5B, laminated with and integrated to photovoltaiccells, electrical connectors; and sealing material;

FIG. 6A shows an embodiment of the invention containing holographicelements and edge-mounted junction box;

FIG. 6B is a close-up view of the embodiment of FIG. 6A;

FIG. 7 is a simplified cross-sectional view showing schematically mutualdisposition of photovoltaic cells and holographic elements in anembodiment of the invention;

FIGS. 8A, 8B illustrate a related embodiment of the invention in top andside views;

FIG. 8C is a diagram schematically showing an array of PV modules eachof which is configured according to the embodiment of FIGS. 8A, 8B;

FIG. 8D is a diagram illustrating a related embodiment of an array of PVmodules;

FIG. 8E illustrates a simplified external supporting structure for usewith an embodiment of the PV module array of FIG. 8C;

FIGS. 9A, 9B present another related embodiment of a PV module of theinvention;

FIG. 10 illustrates a related embodiment of the PV module utilizingthree substrates.

DETAILED DESCRIPTION

References throughout this specification to “one embodiment,” “anembodiment,” “a related embodiment,” or similar language mean that aparticular feature, structure, or characteristic described in connectionwith the referred to “embodiment” is included in at least one embodimentof the present invention. Thus, appearances of the phrases “in oneembodiment,” “in an embodiment,” and similar language throughout thisspecification may, but do not necessarily, all refer to the sameembodiment. It is to be understood that no portion of disclosure, takenon its own and in possible connection with a figure, is intended toprovide a complete description of all features of the invention.

In addition, the following disclosure may describe features of theinvention with reference to corresponding drawings, in which likenumbers represent the same or similar elements wherever possible. In thedrawings, the depicted structural elements are generally not to scale,and certain components are enlarged relative to the other components forpurposes of emphasis and understanding. It is to be understood that nosingle drawing is intended to support a complete description of allfeatures of the invention. In other words, a given drawing is generallydescriptive of only some, and generally not all, features of theinvention. A given drawing and an associated portion of the disclosurecontaining a description referencing such drawing do not, generally,contain all elements of a particular view or all features that can bepresented is this view, for purposes of simplifying the given drawingand discussion, and to direct the discussion to particular elements thatare featured in this drawing. A skilled artisan will recognize that theinvention may possibly be practiced without one or more of the specificfeatures, elements, components, structures, details, or characteristics,or with the use of other methods, components, materials, and so forth.Therefore, although a particular detail of an embodiment of theinvention may not be necessarily shown in each and every drawingdescribing such embodiment, the presence of this detail in the drawingmay be implied unless the context of the description requires otherwise.In other instances, well known structures, details, materials, oroperations may be not shown in a given drawing or described in detail toavoid obscuring aspects of an embodiment of the invention that are beingdiscussed. Furthermore, the described single features, structures, orcharacteristics of the invention may be combined in any suitable mannerin one or more further embodiments.

Moreover, if the schematic flow chart diagram is included, it isgenerally set forth as a logical flow-chart diagram. As such, thedepicted order and labeled steps of the logical flow are indicative ofone embodiment of the presented method. Other steps and methods may beconceived that are equivalent in function, logic, or effect to one ormore steps, or portions thereof, of the illustrated method.Additionally, the format and symbols employed are provided to explainthe logical steps of the method and are understood not to limit thescope of the method. Although various arrow types and line types may beemployed in the flow-chart diagrams, they are understood not to limitthe scope of the corresponding method. Indeed, some arrows or otherconnectors may be used to indicate only the logical flow of the method.For instance, an arrow may indicate a waiting or monitoring period ofunspecified duration between enumerated steps of the depicted method.Without loss of generality, the order in which processing steps orparticular methods occur may or may not strictly adhere to the order ofthe corresponding steps shown.

The invention as recited in claims appended to this disclosure isintended to be assessed in light of the disclosure as a whole, includingfeatures disclosed in documents to which reference is made.

As broadly used and described herein, the reference to a layer as being“carried” on or by a surface of an element refers to both a layer thatis disposed directly on the surface of that element or disposed onanother coating, layer or layers that are, in turn disposed directly onthe surface of the element. A “laminate” refers generally to a compoundmaterial fabricated through the union of two or more components, while aterm “lamination” refers to a process of fabricating such a material.Within the meaning of the term “laminate,” the individual components mayshare a material composition, or not, and may undergo distinct forms ofprocessing such as directional stretching, embossing, or coating.Examples of laminates using different materials include the applicationof a plastic film to a supporting material such as glass, or sealing aplastic layer between two supporting layers, where the supporting layersmay include glass, plastic, or any other suitable material.

For the purposes of this disclosure and the appended claims, the use ofthe term “substantially” as applied to a specified characteristic orquality descriptor means “mostly”, “mainly”, “considerably”, “by andlarge”, “essentially”, “to great or significant extent”, “largely butnot necessarily wholly the same” such as to reasonably denote languageof approximation and describe the specified characteristic or descriptorso that its scope would be understood by a person of ordinary skill inthe art. The use of this term in describing a chosen characteristic orconcept neither implies nor provides any basis for indefiniteness andfor adding a numerical limitation to the specified characteristic ordescriptor. For example, a reference to a vector or line or plane beingsubstantially parallel to a reference line or plane is to be construedas such vector or line extending along a direction or axis that is thesame as or very close to that of the reference line or plane (withangular deviations from the reference direction or axis that areconsidered to be practically typical in the art, in one example—betweenzero and fifteen degrees). A term “substantially-rigid”, when used inreference to a housing or structural element providing mechanicalsupport for a contraption in question, generally identifies thestructural element that rigidity of which is higher than that of thecontraption that such structural element supports. As another example,the use of the term “substantially flat” in reference to the specifiedsurface implies that such surface may possess a degree of non-flatnessand/or roughness that is sized and expressed as commonly understood by askilled artisan in the specific situation at hand.

Embodiments of the invention utilize either single-sided PV cells (alsoreferred to as monofacial PV cells) or bifacial PV cells. A bifacialphotovoltaic cell allows for harvesting of solar energy from both thefront and the back sides of the cell substantially without changing thestructure of the cell. Bifacial solar cells that are currently availablecommercially are known to generally have unequal efficiencies of solarenergy conversion associated with the front and back sides of anindividual PV cell. It is appreciated, when such unequal-efficiencybifacial PV cells (UEB-cells) are assembled into conventional panels orseries such that the “front” or “first” sides (high efficiency sides) ofall the cells are oriented to intercept direct sunlight, while the lowerefficiency or “back” sides are oriented to receive sunlight deliveredindirectly (from scatter, reflection off of the ground, or mountingsurface, for example), the electrical energy output from the resultingPV panels or modules is not optimized. The PV modules containingbifacial cells are usually positioned with the side of a cell havinghigher efficiency generally facing south (in the northern hemisphere),to capture the maximum amount of direct solar radiation possible.Embodiments of a PV module utilizing structurally different dispositionof UEB-cells has been disclosed in a co-assigned U.S. patent applicationSer. No. 13/743,122, the entire disclosure of which is incorporatedherein by reference.

Optionally, embodiments of the present invention employ at least onediffractive optical component that includes a layered structure with adiffraction grating that may be disposed in optical communication with aPV-cell of the module and be co-planar with such PV-cell. Such layeredstructure rating lends itself to being produced in a stampedroll-to-roll process.

Conventionally used PV modules utilize a structural frame to supplementand increase the rigidity afforded by lite(s) of glass (also referred toherein as substrates and superstrate) in juxtaposition with which the PVcells are disposed, while also providing a small measure ofenvironmental protection through the bonding agent of the frame to themodule (Silicone sealant, edge tape, etc.).

In contradistinction with the conventional design, embodiment of a PVmodule according to the present invention is adapted to utilize therigidity afforded by two laminated sheets of glass or transparentplastic (interchangeably referred to herein as “substrates”, betweenwhich the electrically connected PV cells and, optionally, auxiliarydiffractive optical elements are sandwiched) and is devoid of anystructural frame that is external to the substrates. The thickness of anindividual substrate may vary, and generally depends on the structuralrigidity required by the application. For example, in a specificarchitectural application a substrate unit made of laminated to oneanother lites of glass can be as thick as ¾ mm or more, while moregenerally, each glass sheet used in the fabrication of the embodiment isabout 3.2 mm in thickness, resulting in a total module thickness ofapproximately 7.2 mm. In applications that require a higher loadresistance (such as modules structured to operate in hurricane zones,skyscrapers, or where the glass itself is to be used to support part ofthe structural load), an appropriately thicker glass would be used, asshown in the example ofpilkington.com/resources/brglassmechanicalstrengthpdf.pdf.

According to one implementation of the invention, an array (whether alinear array or a two-dimensional) of operably-connected PV-cells isformed and sandwiched (and, optionally, encapsulated with (for example,embedded in) appropriate encapsulating material, as discussed elsewherein this application) in a gap formed between at least two transparentsubstrates disposed in a substantially parallel and spaced-apartrelationship. The array of PV-cells is housed in this gap. In order toincrease a degree of protection of the PV-cell-containing environment ofthe gap from the external influence (such as ambient moisture, forexample), a peripheral seal can be optionally added along the perimeterof the resulting unit (in one case—between the constituent substratesand not extending outside of the substrates, such as to sealingly affixthese substrates to one another. While the examples of embodimentsprovided below do include the description of a peripheral seal, it isunderstood that implementations without such peripheral seal are alsowithin the scope of the invention. In one embodiment, the peripheralseal forms a ring of substantially moisture proof seal along the edgesof the two substrates of the PV module. Such seal may be formed from aconforming elastic material that facilitates environment-caused changesin mutual positioning and/or dimensions of the unit (for example, theexpansion of the components of the unit due to heat).

A non-limiting example of the PV module 100 of the invention is shown,in front and side views, in FIGS. 1A, 1B. Here, a group of PV-cells(formed by one or more of the PV cells, in the latter case optionallyarranged in an ordered array of PV cells) and associated electricalbusses (arranged as discussed later in reference to the embodiments ofthe present invention, for example embodiments 400, 500) is generallydenoted with a shaded area 110 and disposed between the twosubstantially parallel lites of glass 120 a, 120 b that are optionallysealingly affixed to one another with a perimeter seal 124 disposedbetween the lites 120 a, 120 b in a peripheral portion of the unit 100.(Any of these constituent lites of glass can be interchangeably referredto as a “substrate” or, alternatively, the lite that is lower lite in agiven orientation is referred to as a substrate while the lite that isupper lite in such orientation may be referred to as superstrate.Alternatively, the substrate corresponding to the front of themodule—that is, the substrate facing the Sun in operation—may bereferred to as a “front sheet”, while the substrate disposed on theopposite outer side of the module may be referred to as a “back sheet”.)The perimeter seal (or, edge seal barrier) 124 may be optically opaque,translucent, or transparent and made of material such as, for example,desiccated edge seal (such as the seal with desiccated silica particlesin a rubber matrix), silicone or other materials Optionally, thisperipheral or perimeter seal along the perimeter of a lite of asubstrate or superstrate of the module can include the same materialthat is used in the adhesive bonding the substrate and superstrate ofthe PV module together. Examples of appropriate encapsulating materialsinclude EVA, PVB, and thermoplastics such as Surlyn. The front surfaceof the module (that is, the surface facing the Sun in operation) isdenoted as surface 132 a, while the back surface of the module isdenoted as surface 132 b. The peripheral area 134 of the PV module thatdoes not contain a PV cell (if such area is present or available in aspecific embodiment) is defined as an optically transparent closed bandportion, of the substrates (120 a, 120 b). In one example, the width ofthis peripheral area 134 on each side of the area 110 is substantiallyequal to half a difference between a transverse dimension of the area110 and a transverse extent of the PV module 100. In a relatedembodiment (not shown) the peripheral area 134 can be configured to beasymmetric in that on one side of the area 110 the band 134 has a firstwidth while on the opposite side of the area 110 the band 134 has asecond width that differs from the first width. In another example, suchwidth is smaller or bigger than the above-mentioned half a difference.

The edge seal barrier 124, when present, is defined around the peripheryof the module, substantially in the same layer as the PV cells of themodule. In one implementation, the edge seal barrier 124 is about 1mm.+−0.0.5 mm in height (parameter h in FIG. 1B) and between about 2 andabout 20 mm in width (parameter d in FIG. 1A), depending on theapplication. An embodiment of the PV modules laminated withencapsulating materials that differ from the industry standardethylene-vinyl acetate (EVA) (such as, for example, Dupont's Surlyn orother iononer/thermoplastic or silicone based materials), may notnecessarily require such edge seal protection.

Generally, the perimeter seal 124 is shaped as a closed loop or ringwith a width d sufficient to make the seal substantially impenetrable tothe ambient atmosphere and moisture. In FIGS. 1A, 1B the seal 124 isshown to be disposed on the inboard side of the substrates 120 a, 120 bwith a small offset with respect to the edges and/or edge surfaces ofthe substrates (edge surfaces 130 a, 130 b, edges 130 a 1, 130 b 1 forexample). An edge of a substrate of a PV module is defined by anintersection of an edge surface with a top surface or a bottom surfaceof the substrate. In a related embodiment, however (not shown) theperimeter seal may be sized such that a dimensional extent of the sealis substantially equal to a dimensional extent of the PV module. Forexample, an overall width of the seal 124 may be substantially equal tothe overall width of the unit 100 and/or an overall length of the seal124 may be substantially equal to the overall length of the unit 100. Insuch an embodiment, the peripheral/perimeter seal 124 is disposedsubstantially “flush” with the edges of the module such as edges 130 a,130 b (in which case the small offset shown in FIGS. 1A, 1B is notpresent). The PV-module such as the module 100 is preferably devoid ofany structural frame around the perimeter of the module. In other words,there is no housing element (which term refers, generally, to a rigidhousing or frame-like supporting element or other structure affixed tothe embodiment of FIGS. 1A, 1B to add or increased the rigidity of theembodiment).

It is appreciated that an embodiment of a frameless PV module includingmore than two transparent substrates is also within the scope of theinvention. As schematically illustrated in FIG. 1C in side view, theexample of embodiment 140 of the module includes three opticallytransparent substrates 120 a, 120 b, 120 c disposed in a spaced-apartand substantially parallel relationship such as to form a gap betweenany two immediately adjacent substrates. At least one of the two gapsformed between the three substrates contains PV cells that form, whenviewed from the top, at least one PV-cell array. Each of the gaps isshown sealed with a corresponding peripheral seal (124, 144) disposedaround the perimeter of the module 140 in fashion similar to that of theembodiment 100. In one implementation, individual PV cells that aredisposed on one level (for example, between in the gap 124 thesubstrates 120 a, 120 b) are electrically connected to one another in afirst pre-determined configuration to form a first PV cell array, whileindividual PV cells disposed on another level (if present; for example,between the substrates 120 b, 120 c) are electrically connected to oneanother in a second pre-determined configuration to form a second PVcell array.

When both such PV cell arrays are present, the embodiment is referred toas a multi-level PV module. In this case, the first and second arraysmay or may not be operably connected with one another (i.e., they mayoperate independently from one another). In the case of such multi-levelPV module structure, the PV cells of the first array are preferablydisposed such as to not, in operation, cast a shadow on or block fromthe sun the PV cells of the second array and vice versa. FIG. 1D, forexample, provides a top plan view of a PV module 160 in which theindividual PV cells 164 are arranged in a checker-board pattern. If in amulti-level variation of the embodiment 140 of the PV module discussedabove the PV cells at the first level (between the substrates 120 a, 120b) are organized according to the pattern of FIG. 1D, then the PV cellsat the second level (between the substrates 120 b, 130 c) may beorganized in a checker-board pattern that is complementary to thepattern of FIG. 1D. Specifically, the PV cells at the second level maybe disposed at locations that, in the embodiment 160 correspond to thespacings 168 between the PV cells 164, while the spacings between the PVcells at the second level will spatially correspond to the PV cells atthe first level. Elements 170 denote electrical bussing and/or wiringassociated with PV cells of a given level.

The top plan view of a related two-level embodiment 174, structuredaccording to the principles depicted in FIGS. 1C and 1D but containing adifferent number of individual PV cells, is presented in FIG. 1E. Here,the elements 176 depict the PV cells at the first level of theembodiment 172 and the elements 178 depict the PV cells at the secondlevel of the embodiment 172 as seen through the optically transparentsubstrates. For simplicity of illustration, only a few individual PVcells are numbered in FIG. 1E.

A PV module structured with front and back sheets made of glass (a“glass/glass PV module”) has several inherent advantages when comparedto conventional PV modules that employ flexible back sheets (made from,for example, a sheet of plastic material). These advantages includehigher fire resistance, higher humidity and UV protection afforded forthe internal components (such as PV cells, wiring, diffractiveelements); high transparency and low optical birefringence of the PVmodule in operation; reduced and often eliminated “yellowing” of thesubstrate material (due to UV exposure); and a higher rigidity withoutthe use of an integrated structural frame. The glass-to-glassconstruction is also desirable for building integrated applications inwhich laminated glass structures are required for structural/safetyreasons. The glass/glass modules are laminated with the use of materialsand techniques similar to those used for plate glass or safety glasslamination thereby allowing, with proper design, to use the embodimentsof the PV modules of the invention in architectural applications. Atypical laminated structure of a PV module includes a tempered glasssubstrate, adhesive, PV-cell-containing layer, a hologram layer (ifapplicable), adhesive, and tempered glass superstrate. The structure islaminated in a heated environment with vacuum and pressure applied tothe structure progressively.

FIGS. 1E, 2, 3, and 4 are diagrams showing, in top views and in greaterdetail, related embodiments of a PV module (whether single- ormultiple-level) configured according to the idea of the invention. Theindividual PV cells in these embodiments (whether arranged in ordered PVcell arrays or not) are disposed on a single level and/or, in additionor alternatively, on multiple levels of a corresponding PV module.

FIG. 2, for example, presents a top view of an embodiment 200 of theframeless PV module containing thirty two (32) PV cells 210appropriately electrically connected with bussing or wiring 214 andarranged in a rectangular two-dimensional array disposed between atleast two mutually-parallel lites of glass (such as lites 120 a, 120 bof FIGS. 1A, 1B). The electrical connections 214 operably lead to thejunction box (or J-box) 220, which is used to interconnect the modulewith the external electrical wiring and systems and/or other modules.The cell-to-cell spacings 230 a, 230 b, separating the individual cells210 in rows and columns, are appropriately controlled and dimensioned toensure that a predetermined portion of sunlight incident onto the PVmodule 200 in operation through the front sheet is transmitted throughthe PV module 200 (i.e., through the lites 120 a, 120 b) to illuminate ascene behind the module 200, which is otherwise blocked from the Sun bythe module 200.

A transparent area formed, as a closed band, around the array of thecells 210 between the edge 120 a and the outer boundary of the array ofthe PV cells 210 (cell-to-edge separation or clearance), is optional. Inan embodiment where such cell-to-edge separation is present, however,the structure of such peripheral transparent band preferably satisfiestwo conditions. On the one hand, the cell-to-edge separation may besized to be greater (wider) than an extent of a portion of an externalfixator (such as, for example, clamp or a like contraption) thatoverlaps with the module 200 and/or extends towards the PV cells 210inward with respect to the edge (for example, edge 120 a) of the module200 when used in juxtaposition with the embodiment to attach theembodiment to a surrounding structure or support for proper operation.On the other hand, in addition or alternatively, the cell-to-edgeseparation may be sized to be greater (wider) than the extent of ashadow that such external fixator casts on the module during its typicaltime of operation. In applications in which the frameless PV module isto be used with external attachments or mounting systems that mightshade the cells in the module (such as conventional mounting clips fromtraditional rooftop mounting PV systems, for example), the clearancearound the edge of the module and the cells in the module is increasedsuch as to account for the module-intruding shading and the shadingcaused by the height of the mounting elements as the sun movesthroughout the day and season. The extent of the shadow cast can beestimated using the principles outlined, for example, in Thakkar, N.,Cormode D., et al., “A simple non-linear model for the effect of partialshade on PV systems” (Photovoltaic Specialists Conference (PVSC), 201035th IEEE; Honolulu, Hi., IEEE: 002321-002326; 2010).

FIG. 3 illustrates a related embodiment 300, in which a two-dimensionalarray of PV cells 310 includes columns 312 (of PV cells) separated fromone another by spacings 330 such that in each column 312 the immediatelyneighboring cells 310 are substantially adjoining each other. Again, asin the embodiment 200, the embodiment may be configured to include anoptional cell-to-edge spacing (not shown).

FIG. 4 illustrates a related embodiment 400, in which individual PVcells 410 are arranged in a two-dimensional array such that a given PVcell 410 is substantially adjoining each and every immediatelyneighboring PV cell, thereby leaving a minimal amount of spacing betweenor among the neighboring cells. Depending on the shape of individual PVcell, some small areas in the overall foot-print of the PV-module (suchas, for example, areas 420) may remain substantially transmissive tosunlight incident substantially normally to the surface of the front orback surfaces 132 a, 132 b of the module 400.

In the embodiments of the invention that are structured to have wiring(or bussing, or electrical connectors) between the individual PV cellstowards the back or front surface of the module for electricalinterconnections (for example, to provide electrical contact(s) with aback-mounted junction box), the glass substrate/superstrate (forexample, substrate 120 a) may be configured to include openings 510.Such openings, if present, are judiciously dimensioned to allow thewiring to pass therethrough, as shown in FIGS. 5A, 5B. (FIG. 5Aillustrates a substrate 120 a with the openings 510 prior to assembly ofthe PV module; FIG. 5B shows a portion of the already-assembled andlaminated PV module with PV cells 520 and bussing 214.) To form theopening, in one implementation sheets of glass are drilled or ablated toform through-holes in the precisely defined locations and thenoptionally tempered. The drilled holes 510 can be additionally andoptionally treated to have mechanical stress relieved (with process(s)such as chamfering, grounding of edges and the like).

In reference to FIGS. 6A, 6B, on the other hand, in applications wherethe inter-PV-cell wires/connectors/busses are not required to be drawnor pulled through a substrate and/or superstrate of the PV module, thewiring or bussing 214 may be extended towards an externally disposedelectrical circuitry (such as a junction box 610) through one of thesides and/or over the edge(s) of the module (for example, the edge 130a). The embodiments of FIGS. 6A, 6B additionally includeinternally-disposed holographically-defined diffractive optical layersor elements 620 in optical communication with corresponding PV cells630. Examples of such diffractive elements, methods of theirfabrication, and techniques for integration of these elements with othercomponents of the PV module are described, for example, in U.S. patentapplication Ser. No. 13/682,119 the entire disclosure of which isincorporated herein by reference.

A shown in a cross-sectional sketch representing a related embodiment700 of FIG. 7, an embodiment may be a multi-portion (or multi-period)embodiment of a PV module and include first and second portions 708,712. (Additional portions or periods, optionally present, are indicatedwith ellipses 716.) Each of the portions or periods 708, 712 contains acorresponding bifacial PV-cell or array of cells (720, 722) that issurrounded by (and substantially co-planar with)respectively-corresponding holographically-recorded diffraction gratinglayers (730, 732) or (736, 738). The holographic-grating-containinglayers 730, 732, 736, 738 include, in one embodiment, transmissive bulkholographic diffraction gratings recorded in a dichromated gelatinlayer. Pairs of the grating-containing layers can be cooperated with thecorresponding bifacial PV-cell (on the sides of such cell) with orwithout spatial gaps separating them from the cell. Each of thegrating-containing layers 730, 732, 736, 738 may be incorporated into anencapsulant layer which is used laminate bifacial PV-cells 720, 722together with the corresponding pairs of gratings (730, 732) and (736,738) to front and back covers 704, 740 of the embodiment. Various arrowsin FIG. 1 indicate propagation of sunlight incident onto the surface 788of the embodiment 700.

When an embodiment of the invention includes a PV-module containingbifacial PV cell(s), there exists a practical problem that the junctionbox of the module will block solar radiation from impinging onto atleast one side of the PV cell. To obviate this common problem, in anembodiment of the invention the junction box is placed at the back ofthe module or in the vicinity of the edge of the module. The shading ofthe PV module is therefore minimized or even eliminated and the powerloss associated with decreased local illumination (as well as possibledetrimental effects such as extra heating, serially limiting the currentin a string, and the like) is reduced. FIGS. 2-4, and 6A, 6B illustrateseveral examples of operably appropriate cooperation between thejunction box (220, 610) and the PV cells (210, 310, 4101, 630). Inimplementation of frameless PV-modules that do not use bifacial cells oredge mounted junction boxes, a medium or large format junction box maybe juxtaposed with a surface at the back of the module.

Some embodiments of a frameless PV-module (such as, for example,embodiments similar to the embodiments 200, 300) are structured toensure that a portion of incident ambient light is converted intoelectrical power and a portion of such incident light is transmittedthrough the spacings (230 a, 230 b, 330 a) between or among the cellsthereby defining the PV module as being partially transmissive. Sostructured, an embodiment of a frameless PV-module of the invention isdimensioned, therefore, for use as part of a ceiling or windows in abuilding where it is desired to illuminate the interior of the buildingwith natural light while utilizing sunlight for electrical powergeneration.

The overall light transmittance T through the so-structured framelessPV-module can be calculated as T (%)=100%[1-R-A], where R and A denotereflectance and absorbance of sunlight by the module. Assuming a 4A %reflection from glass and using the Beer-Lambert Law the transmittancevalue is rewritten as:T(%)=100%*0.96*−.alpha.d*[1−AS+NAC+AW+AJA]  ##EQU00001 ##

Here, .alpha. is the absorption coefficient of the transparent areas ofthe PV module, d is the module thickness; A.sub.S is the area of anexternal to the frameless module supporting structure or fixator thatcasts shadow on the module; N is the number of PV cells; A.sub.C is anarea of a single PV cell; A.sub.W is the area occupied by the electricalwiring (bussing, connectors); A.sub.J is the projected onto the modulearea of the J-box, and A.sub.z is the total area of the PV module.

In further reference to FIG. 2, and when the PV module employs bifacialPV cells, once the number of bifacial cells and the total module areaare determined to achieve the desired transmission of sunlight throughthe module, and once the dimensions of the peripheral transparent area240 are known, the extend and dimensions of the spacings 230 a, 230 bcan be determined and varied to achieve various optical effects in lighttransmitted through the embodiment of the frameless module. For example,by making the horizontal and vertical spacings 230 a, 230 bsubstantially equally wide a substantially uniform illumination of thescene behind the PV-module can be achieved. Minimizing one of thesewidths while maximizing another causes the light to form, intransmission through the module, a regularly-spaced in one dimensionpattern of light (“light columns”), as seen in FIG. 3, for example. Asthe skilled artisan will appreciate, various aesthetics possibilitiescan then be achieved within the constraints of the maxim transmittancepossible.

As the light transmission of the PV module is increased, more lightinteracts with the surfaces behind the module and is scattered/reflectedback towards the rear (with respect to the incident light) surface ofthe bifacial PV cells, thereby increasing the amount of energy producedper cell in the module. Modules produced with increased spacing betweenthe cells will have a relatively larger surface area to radiate heat,lowering their temperature and again increasing the energy generated percell.

As is readily appreciated by a skilled artisan, a problem of reliableinterconnection between or among the individual PV modules remains. Forexample, “seam areas” between the interconnected modules remain,arguably, the weakest (in a structural sense) areas of the resultingarrayed contraption. In addition, in the case when arrays ofinterconnected modules are formed from the frameless modules, each ofthe constituent modules has to be maintained in a fixed spatialrelationship with respect to the surrounding modules which, in turn,often begs for employment of a supporting structure such as a frame onthe whole perimeter of a constituent module is rested.

The present invention additionally solves a persisting-in-the-artproblem of forming a reliable structural connection betweenimmediately-neighboring PV modules of a PV-module array. This isachieved by judiciously and intentionally structuring a constituent PVmodule of the array to have its substrates be transversely shifted withrespect to one another (in a plane parallel to a plane of a givensubstrate) and positioning the neighboring PV modules with anintentional overlap between their corresponding transversely-shiftedsubstrates. An appropriately dimensioned and intentionally-formedtransverse shift between the substrates of a given module is configuredalong at least one of the spatial extents of such module, as discussedbelow. Generally, the substrates of an embodiment of the invention arecongruent with one another, which term defines elements that areidentical in form, or coinciding exactly when superimposed. In oneimplementation, the substrates may be plane-parallel plates such asglass plates with dimensions of W.times.L, where W is between 0.16 m and1.6 m, while L is between 0.16 m and 2.5 m. In another implementationthe substrates may be made of sheets of optically transparent plasticmaterials such as (width: 0.16 m to 1.6 m).times.(length: 0.16 m to 2.5m). In a specific case, the substrates are plates appropriately curvedto define a PV module having a convex or concave shape. Transversedimensions of a typical PV cell are 0.156 m by 0.156 m. Theintentionally-defined transverse shift between the substrates is, in oneexample, on the order of half a centimeter; in a related embodiment iscan be as large as several centimeters.

Non-limiting examples of the implementation of the idea of the inventionare illustrated in FIGS. 8A, 8B, 8C, 8D, 9A, and 9B.

As shown in top and side views of FIGS. 8A, 8B, for example, anembodiment 800 of the PV module is bound by the two substrates 120 a,120 b that are substantially equally dimensioned but intentionallyshifted transversely with respect to one another (as shown—along x-axis)by a distance xx. The amount of such intentional transverse shiftexceeds the amount of incidental shift that may occur during theassembly of the embodiment 100 of FIGS. 1A, 1B, and in oneimplementation exceeds 5 mm. While in the embodiment 100 a footprint ofthe substrate 120 a on a plane defined by the substrate 120 b (that is,a normal projection of the substrate 120 a along the z-axis on suchplane) substantially co-extensive with the substrate 120 b (asillustrated in FIG. 1A), the embodiment 800 is structured differently.Here, while a first footprint (of the substrate 120 a on a plane definedby the substrate 120 b—that is, a normal projection of the substrate 120a along the z-axis on plane shown as 820) and a second footprint (anormal projection of the substrate 120 b on the same plane) aresubstantially equally dimensioned rectangles, these footprints are notco-extensive but are shifted with respect to one another along oneextent of the substrates (in this case—along x-axis) such that normalprojections of the edges 130 a 1 and 130 b 1 on plane 820 are parallelto one another and separated by the distance xx. The term “co-extensive”is defined as “having the same spatial boundaries”. The area 810,bounded by the substrates 120 a, 120 b and the ring 124 of the sealingmaterial, contains at encapsulated PV cell layer including at least onePV cell (by analogy with the area 110 discussed in reference to FIGS.1A, 1B). So disposed, an upper substrate (as shown—substrate 120 a)forms an “overhang” or visor 830 over the lower substrate (asshown—substrate 120 b), while on an opposite side of the module acorresponding portion of the lower substrate forms a “lip” 834protruding from under the upper substrate.

Accordingly, FIGS. 8A and 8B illustrate a photovoltaic module thatincludes first and second optically transparent substrates. The firstoptically transparent substrate has a first longitudinal extent definedby first and second edges of the substrates that are substantiallyparallel to one another. The first substrate also has a first transverseextent defined by third and fourth edges that are substantially parallelto one another. The second optically transparent substrate has a secondlongitudinal extent defined by fifth and sixth edges that aresubstantially parallel to one another and a second transverse extentdefined by seventh and eighth edges that are substantially parallel toone another. The first longitudinal extent is substantially equal to thesecond longitudinal extent, and the first transverse extent issubstantially equal to the second transverse extent. Between the firstand second substrate there is an operationally-active layer including aPV cell—whether monofacial or bifacial—and a ring of sealing materialsealingly attaching the first and second substrates to one another alongthe perimeter of the operationally-active layer. The PV module isconfigured such that at least one of the following conditions issatisfied: (i) a first line representing a normal projection of thefirst edge on a plane defined by the second substrate is substantiallyparallel to and separated from a line representing the fifth edge; and(ii) a second line representing a normal projection of the third edge ona plane defined by the second substrate is substantially parallel to andoffset by a second distance from a line representing the seventh edge.

The purpose of the above-identified intentional transversely-shifteddisposition of the substrates 120 a, 120 b during the construction ofthe embodiment 800 is to facilitate a specific configuration of an arrayof the PV modules, in which the two immediately neighboring PV modulesare judiciously sequenced to ensure an overlap between a visor of onemodule with a lip of another. FIG. 8C shows a side view of an array 850of the PV modules drawn not to scale and structured according to anembodiment of the invention. Individual modules 852A, 852B, 852C arepositioned to form a string of the modules along the x-axis such that anintentionally formed visor of an upper substrate of one module overlapswith an intentionally formed lip of a neighboring module. Ellipses 854indicate the presence of additional modules in the array. At least aportion of the gap between the overlapping portions of substrates of theimmediately neighboring modules is filled with an adhesive and/orsealing material 860 with a purpose of sealing/protection again theatmosphere elements and/or mechanically bonding the overlapping modulesto one another to increase the overall structural stability of themodule array. At least those residual gaps or openings 866 (between thecorresponding edges and edge surfaces of the immediately neighboringmodules of the array 850) that, in operation of the array, are disposedupwards and towards the Sun may be additionally covered/sealed withadditional sealant 870 (such as, for example, with a weather-sealingtape and/or U, T or otherwise shaped gasket; the latter additionallycushioning the two immediately neighboring modules from hitting eachother); at least some of the gaps on the lower side of the array may becovered as well. For simplicity of illustration, only gaps 866 on theupper side of the array 850 are shown protected with the sealant 870.

A specific implementation, in which the optionally flexible gasket orother sealing material 878 is interposed between the outer-portions (theones installed to face the sky, in operation) of the two immediatelyneighboring modules 852A, 852B, to provide for sealing protectionagainst the atmospheric elements and/or be configured as a mechanicalbuffer to protect the edge surfaces of the corresponding substrates ofthe modules 852A, 852B from directly contacting each other. The lowersurface 880 of the gasket 878 may optionally extend all the way to thesurface a of the underlying substrate. While the gap (marked as 866 inFIG. 8D) between the opposing, “bottom” substrates is not shown to befilled with a flexible sealing material, it can be if desired.

Referring again to FIGS. 8A through 8D, the array 850 is assembled insuch orientation that electrical junction boxes 610 of the individualmodules (not shown) are disposed on the side which, in operation, isturned away from the sky. Due to the presence of the overlap of thesubstrates belonging to the neighboring modules, one of the neighboringmodules mechanically supports the structure of another. As a result, theonly external load-supporting structure, required by the string 850 ofoverlapped (tiled upon one another) PV modules during the installationfor operation, is two rails or beams 876 extended along the x-axis underthe opposing edges of the array, as schematically shown in FIG. 8E. Suchsimplification of the external supporting structure afforded by aconfiguration of the embodiment of the invention is operably andcost-wise advantageous as compared with a supporting structure requiredby a PV-module array that is composed of individual PV-modules 100, forexample, dimensioned without the intentional offset dd (which includessupporting rail or beams extending along the edges of individual modulesboth in x- and y-directions).

It is appreciated that in a related embodiment 900 the two substrates120 a, 120 b can be disposed to define two intentional offsets, yy andxx (along the extents of the module corresponding to y- and x-axes,respectively), as schematically shown in FIGS. 9A, 9B. An array of suchPV modules is assembled to define a structure in which a visor formed byan upper substrate of one module along each of the x- and y-axes isoverlapped with a respectively-corresponding lip formed by a lowersubstrate of an immediately-neighboring module. The size of each of suchoffsets, in one implementation, is at least 5 mm or more, to provide forproper inter-gap sealing (the gaps defined between the so-overlappingportions of the substrates are at least partially filled with thesealing/adhesive material, as discussed previously).

Furthermore, a person of ordinary skill in the art would readilyunderstand that the idea of the invention can be extended to a“triple-substrate” structure of a PV-module (such as that of FIG. 1C,for example. In this case, the middle of the three substrates istransversely shifted (offset) with respect to both of the outersubstrates, either along one or both of the extents of the PV-module, toprovide for appropriate mating of the two or more PV modules into a 1Dor 2D array of the PV modules by analogy with those disclosed above. Aschematic diagram of an individual “triple-substrate” PV module 1000configured to implement the idea of the invention is shown in FIG. 10.It is understood, therefore, that, in comparison with an embodiment ofFIGS. 8A, 8B, 9A, 9B, the embodiment of FIG. 10 additionally providesfor a third optically transparent substrate that has first longitudinalextent (defined by ninth and tenth edges that are substantially parallelto one another) and first transverse extent (defined by eleventh andtwelfth edges that are substantially parallel to one another). In thiscase, the first and third substrates are disposed in parallel to oneanother and on opposite sides of the second substrate. A first polygonrepresenting a normal projection of a perimeter of the first substrateon the plane defined by the second substrate is substantiallyco-extensive with a second polygon representing a normal projection of aperimeter of the third substrate on said plane. In this embodiment, oneor more second PV cells can be disposed in a volume between the secondand third substrates. The second and third substrates are sealed with asecond flexible sealing material disposed therebetween between along aperimeter of the operationally-active layer that contains the second PVcells, to sealingly attach said second and third substrates to oneanother.

While the preferred embodiments of the present invention have beenillustrated in detail, it should be apparent that modifications andadaptations to those embodiments may occur to one skilled in the artwithout departing from the scope of the present invention.

For example, an a related embodiment (not shown), a frameless PV modulemay include an array of sub-PV-modules that are both mechanically andelectrically connected through flexible joints and, optionally, have anoverlaying cover layer shaped to include a dome-like structure.Implementations of flexible PV modules are discussed, for example, inthe co-assigned U.S. patent application Ser. No. 13/675,855. Similarly,a related embodiment of the invention may include various encapsulatingmeans directed to protect PV cell array from being exposed to theambient as discussed, for example, in a co-assigned U.S. patentapplication Ser. No. 13/682,119. Disclosure of each of these two patentapplications are incorporated herein by reference in its entirety. A PVmodule containing any of the additional elements and features disclosedin patent documents incorporated by reference herein are within thescope of the present invention.

The invention claimed is:
 1. A photovoltaic (PV) module systemcomprising: a photovoltaic module having a first optically transparentsubstrate and a second optically transparent substrate bounding a cavitytherebetween; a PV cell located in said cavity between said firstsubstrate and said second substrate; said PV cell being a first cell ofa plurality of electrically interconnected PV cells disposed betweensaid first substrate and said second substrate, a sealing materialdisposed in said cavity between said first substrate and said secondsubstrate around a perimeter of said PV module to provide a seal aroundsaid perimeter of said PV module; and a hole through said firstsubstrate and/or said second substrate and an electrically conductingmember electrically connected to the PV cell and passing through saidhole.
 2. The system of claim 1 wherein said plurality of PV cellscomprise bifacial PV cells.
 3. The system of claim 1 wherein saidsealing material comprises an encapsulant covering a photovoltaicallyoperable surface of the plurality of PV cells.
 4. The system of claim 1further comprising an encapsulant covering a photovoltaically operablesurface of the plurality of PV cells, said seal being locatedperipherally relative to said encapsulant.
 5. The system of claim 1further comprising an external supporting structure for holding saidmodule located at a plurality of locations on a perimeter of said PVmodule, said supporting structure extending inwardly from said perimeterto cover a portion of said closed band.
 6. The system of claim 5 whereinsaid supporting structure extends inwardly from said perimeter less thana width of a peripheral area around said plurality of electricallyinterconnected PV cells lacking a PV cell and defining a closed band. 7.The system of claim 6 wherein said supporting structure comprises aplurality of clamps separated from each other along said perimeter. 8.The system of claim 1 wherein said PV module is devoid of any structuralframe around said perimeter.
 9. The system of claim 1 wherein said PVmodule is devoid of a substantially rigid housing.
 10. The system ofclaim 1 wherein said seal is flush with outside edges of said firstsubstrate and said second substrate.
 11. The system of claim 1, furthercomprising an electrical junction box coupled to the module such that,in operation, a shadow of said electrical junction box cast by sunlightdoes not fall on a PV cell of the plurality of PV cells.
 12. The systemof claim 11 wherein said electrical junction box is located outside saidcavity and laterally relative to said plurality of PV cells in adirection parallel to a longitudinal dimension of said first substrateand/or said second substrate.
 13. The system of claim 11 wherein saidelectrical junction box is located outside said cavity and mounted at aperimeter of said first substrate and/or said second substrate.
 14. Thesystem of claim 1 wherein a dimensional extent of said seal issubstantially equal to a dimensional extent of said PV module.
 15. Thesystem of claim 1, wherein said first substrate and said secondsubstrate are glass plane-parallel plates.
 16. The system of claim 1further comprising an electrically conducting member electricallyconnected to the PV cell and extending laterally through an edge of thecavity to connect to a junction box located at an edge of said firstsubstrate and/or said second substrate.
 17. The system of claim 1wherein said PV module is ungrounded electrically and conductivelyduring operation.
 18. The system of claim 1 further comprising aperipheral area around said plurality of electrically interconnected PVcells lacking a PV cell and defining a closed band, a width of saidclosed band corresponding to a difference between a transverse dimensionof the PV module and a transverse dimension of plurality of electricallyinterconnected PV cells.
 19. The system of claim 1 wherein said sealcomprises a substantially moisture proof seal sealingly affixing saidfirst substrate to said second substrate.